Canada Day is a holiday based on history, a celebration of our heritage as Canadians. And this year, the federal government has given us a special gift -- it has unlocked the door to documents that will help us discover more about our past.

The good news came on Tuesday morning, when MPs gave unanimous consent to a change in Canada's statistics law. That sounds, well, boring, so it's no real surprise that the controversial same-sex marriage legislation that was passed a few hours later took all the attention.

But the amendment to the Statistics Act matters, too, especially to the tens of thousands of Canadians who have been lobbying MPs for the change for several years. They include genealogists and historians, not the usual suspects when it comes to fighting for a change in a law.

The amendment allows census returns to be opened for research 92 years after they are compiled. That means we will get immediate access to the national census taken in the spring of 1911, and all of the information it contains about people, relationships, occupations and more.

And we'll be able to see the 1916 census of the Prairies in 2008, the 1921 national census in 2013, and another census every five years after that.

This is great news for anyone with an interest in the country's history. So if you hear a lot of cheering in your neighbourhood this weekend, it might not be Canada Day celebrants, it might just be historians getting out of hand.

A census represents a view of the country and its people -- all of its people -- at one point in time. As a source of historical information, it can't be matched.

Despite the obvious value of opening these old records, there was a real risk that they could have been locked away forever, which would have imposed severe limits on our understanding of our collective past.

The problem was that when the census was taken, there was a promise that the information would be kept confidential. That promise was interpreted in some federal government circles as being a promise for all time -- even long after the people who provided the information were dead.

And so, with the records hidden from view, researchers started writing letters, signing petitions and filing access-to-information requests in an effort to have them opened.

The census returns up to 1901 had all been released, after all, without causing a commotion. Still, the government refused to let anyone see the census returns from 1906 and later.

I must admit to a personal bias here. I was one of a dozen people from across Canada who got together to sue the government for the release of the 1906 census, which covered just the high-growth (at that time, anyway) Prairie provinces.

We were pressing forward, confident of victory, and ready to argue our case in court when the government suddenly decided, in January 2003, that it could open up the 1906 census after all.

But it still drew the line at the 1911 one. It's taken the firm resolve of some keen supporters inside government -- Ontario Liberal Senator Lorna Milne tops the list -- along with private individuals to ensure that we would finally get access to the old documents.

Milne first raised the issue about access to historic census returns in 1998, after Statistics Canada said it had concerns about the legality of releasing them.

StatsCan has an understandable concern, because much of its work would become much more difficult if Canadians stopped trusting it. And going back on a promise of confidentiality doesn't do much to build trust.

That said, there surely must be a time limit to any promise to keep things quiet. I'd guess that King Tutankhamen didn't want the world to know all his secrets, but that hasn't stopped anyone from putting his assets on display.

And I'm sure that my great-grandfather William Montgomery wouldn't have wanted his neighbours, back in 1911, to know how much money he made. But old Will has been at rest, as they say, in Vancouver for more than six decades. I'm not convinced that he cares about his old secrets any more.

The amendment that was passed by MPs this week eliminates any need for further discussion about historic census records for years to come. That is a tremendous boost for anyone doing historical research, for whatever reason, and it's fitting that the change came so close to Canada Day.

Friday's holiday is our chance to remember the founding of our nation, and to look back at how Canada has evolved through the years. All the flag-waving and face-painting is nice, but there would be no reason for Canada Day without Canadian history.